What's up Gang? I have been getting misfire readings on multiple cylinders. I did a complete tune up of the following...Oil, Oil Filter, Air Filter, Spark Plugs...still misfire. Then replaced the coil pack, still misfire. Changed all six fuel injectors, still misfires. Before doing all of this, I tried all the home remedies like SeaFoam, Mystery Oil, fuel additives...What's been your guys' experience with this? Thanks A LOT. Below is my Jeep info:

2001 XJ Sport 4.0

 

I’m having the same issue and have done all the same things. Very frustrating

 

4 items, only 1 of which has any possibility of causing a misfire. Not a good batting average. (And if we cound the SeaFoam, etc., it's even worse.


Two more rounds from the parts cannon, still no success. I'm seeing a pattern here. At least these two might be related to a misfire, but they could have been tested for free.

My experience, and that of many of us, is that testing works a lot better than firing the parts cannon. It's cheaper, usually faster, and a lot less frustrating.

Have you thought of puling any codes? Many auto parts stores will read them for free. That should be your first move, long before you buy any parts or magic potions.

 

Do a compression check and a cylinder leakdown test. You may have some burnt exhaust valves. Just saying.

 

I've had the same experience with wife's '01Sport. Local wrenchs say bad ECU. Not that I put a lot of faith in them. $$$! I solved the check light problem by getting one of those OCDB performance plug-ins. Stopped the complaints tempoarily. Probably not the best solution, but doesn't seem to be detrimental, and even improved mileage.

 

Blue Ridge Mark,

I may not even have a misfire. I was going on a hunch. Your reply is a showcase to Mankind of what it means to be a Keyboard Commando in a dangerous world full of new mechanics ridiculously vulnerable enough to ask for help. Without Red-Blooded American Heroes like you, Mark, the world of Jeep Forums would likely fall into the hands of Toyota or Land Rover extremists. Thank you for your service and for keeping vigilant watch for all of us. God Bless.

 

I gave you useful information. What you do with it is your business. If the most important thing in your life is to never be corrected, well, have fun with that.